Melamine Residue And Disappearance In Tilapia

The artiele established the determination of melamine in feeds and the rapid determination of melamine in aquatic products by high performance liqiud chromatography. There were aquatic product and combinative feed, feed material being detected by HPLC in ZhanJiang area. The residual elimination of melamine in Tilapia also studied. The results as follows:1. Determination of melamine by high performance liqiud chromatography in feed was established.Referring to literature, according to the absorption lights Peetrum,chemieal constitution,and other peculiarity of melamine, optimizing the comPosition and pereentage of mobile phase, wavelength, flowrate,and PH. Chromatography separation was achieved on a DIKMA C₁₈(250mm×4.6mm, 5μm); column using acetonitrile and hydronium (V/V,8:92).The UV deteetion wavelength was set at 236nm,a flow rate of 1.2mL/min with a column temperature at 40℃. Retention time were 15.58min.Extraction method (feed): Sample was extracted with acetonitrile-water under acid condition and Stripping by dichloromethane, cleand-up using the solid phase extraction (SPE) with the HyperSep Retain-CX column. Analysiswas performed using HPLC, external standardswere used for quantitative determination. Results:The calibration curves showed good linearity in the range of 0.2～10 mg/L for melamine. The correlation coeff icents was 0.9995. The recoveries were 85.5%～95.6% at spiking levels 1.0-10.0mg/kg and relative standard deviations were less than 5%. The detection limit of melamine was 0.2 mg/kg.2.Determination of melamine by high performance liqiud chromatography in aquatic product was established. Referring to the determination of melamine in feed, optimizing the extraction method in aquatic product.Extraction method (aquatic product): Sample was extracted by methanol-water and trichloroacetic acid, then the extracts were ready for determination by HPLC after centrifugalized and filtered. Results: The calibration curves showed good linearity in the range of 0.2-10.0μg/mL for melamine. The correlation coefficent was 0.9989. The recoveries were 85% ⁹1% and relative standard deviations were 4.2～6.4% in the spiked range of 0.5¹0.0 mg/kg in aquatic products. The limit of quantitative was 0.5mg/kg.3. Melamine background content in aquatic product and animal feeds in ZhangJiang by the multi-residue determination method. The result demonstrated that the melamine was no detected in aquatic product, 4.3% frozen combinative feed, 4.5% frozen feed material in our examination. Melamine may be possibly artificially added in high proteide feed during producing; aquatic product is security.4. The objective of this study was to investigate the residue and disappearance of melamine in the entrails and muscle of Tilapia. 300 fish (Body weight:12.0±2 g) were randomly divided into 5 groups. Each group was fed administrating diet with 0,1000,5000,10000,50000mg/kg melamine respectively for 50 d and the melamine concentration were determined in the entrails and muscle of Tilapia on every 5 days. Then switching feed the basal blank diet 10d and determine the residual melamine levels on everyday. Results showed that the weight of Tilapia in adding melamine to the dietary for 50 days was no significant difference between each group (P>0.05). Melamine residual levels in entrails and muscle increased obviously with levels of melamine in feeds (P<0.05).At lower dietary content(1000,5 000 mg/kg),melamine residual levels were between 2～20mg/kg, at higher dietary content(10 000,50 000 mg/kg),melamine residual in excess of 40mg/kg, and that the levels of melamine residual in entrails is higer than in muscle(P<0.05). After withdrawing melamine diets 5 days , the melamine concentrations in entrails and muscle were decreased significantly, and below 2mg/kg, then slow declining. The time of melamine disappearance in muscle is longer than in entrails .